OUTLINE: This is a randomized, double-blind, placebo-controlled, multicenter study. Patients are randomized to 1 of 2 treatment arms. Arm I: Patients receive oral melphalan and oral prednisone on days 1-4. Patients also receive adjuvant enzyme therapy with oral Wobe-Mugos E 3 times daily beginning prior to or on day 1 of the first course of chemotherapy. Arm II: Patients receive melphalan and prednisone as in arm I. Patients also receive an oral placebo 3 times daily as in arm I. Treatment continues for a minimum of 12 months to up to 4 years in the absence of unacceptable toxicity. Patients continue on melphalan and prednisone on a 4-week course until achieving maximum response or plateau phase and then receive 2 additional courses of therapy. Quality of life is assessed at baseline; at 1, 3, and 6 months and every 6 months for up to 4 years during study; and then at end of study. Patients are followed for survival for 1 month after completing the study and all patients receive the enzyme product.